critters in my shrimp tank (ID?)

[JohnPaul]

One thing I've learned in keeping dwarf shrimp in fish-free tanks is there are various little critters--ranging from worms to nematodes to all sorts of other things--that often get eaten in fish tanks but can suddenly thrive in a tank that is free of fish.

I recently bought some plants online and about two weeks after getting them, I saw some hydra in my tank. While these normally are not a huge issue, in a shrimp tank they are because with their stinging tentacles a hydra (some can get up to 1/4" in size) can overpower and kill a baby shrimplet.

The other thing I've found is 5 or 6 of these critters that I *think* may be juvenile damselfly larvae. However, I've looked online for pictures of those and usually the pictures I see are creatures that are much longer & thinner in body shape than what I have. (The picture below is the largest one I could find, and it is only not even 1/4" long). Anyone able to help me ID this beastie? I've pulled a bunch out already but my gut tells me there are more of them lurking, so I need to try to figure out if this is going to be a serious problem or not.

Thanks for any help!

 

[taylorodw]

I agree it looks like damselfly... but I agree that shape does look a little different.

Bugs you might encounter in your aquarium

That is the best source I've found.

 

[JohnPaul]

I did some more poking around, it apparently is a dragonfly larva. So very similar to the damselfly, but dragonfly larvae are shorter & fatter (like mine). Same sort of lifecycle, same sort of predatory behaviors. So a real threat.

Looks like I'm stuck keeping an eye on the tank and pulling them out as I see them...

 

[taylorodw]

After reviewing the link I posted, you're right it does look much more like dragonfly larvae than damselfly.

Good luck. I suppose any fish large enough to eat those would also be a threat to the shrimp.

 

[Crepe]

One on the left is a hydra. They can sting and eat baby shrimp. I would get rid of them as you see them. You can kill them with an antibiotic but I just can't remember the name. So I'll get back to you on that.